External regulation of internal air vent structure for hammermill

ABSTRACT

An air valve structure in connection with a hammermill type of grinding mill to regulate the internal air recirculation system of said mill. Said air valve structure consists of a vent in a door supported plate member forming one side of the grinding chamber, a vent closure member, a screw rod supporting said vent closing member, said screw rod being threaded through the supporting door of said plate member, and means externally of said door operating said rod and said closure member to regulate said vent.

United States Patent Olson EXTERNAL REGULATION OF INTERNAL AlR VENTSTRUCTURE FOR HAMMERMILL [76] Inventor: Robert P. Olson, Rt. N0. 2, Box

657, Mound, Minn. 55364 [22] Filed: May 8, 1974 [21] Appl, No: 467,921

[52] US. Cl. 241/59 [Sl] Int. Cl." BOZC 23/26 [58] Field of Search 24H5) [56] References Cited UNITED STATES PATENTS 3311494 4/]967 Petersonv. 241/59 X 3.598326 8/[971 Penncll H 24l/59 X Sept. 9, 1975 1702686ll/l972 Jacobson 241/59 Primary Examiner-Granville Y. Custer, Jr.

Attorney, Agent, or FirmLeo Gregory 57] ABSTRACT An air valve structurein connection with a hammermill type of grinding mill to regulate theinternal air recirculation system of said mill. Said air valve structureconsists of a vent in a door supported plate member forming one side ofthe grinding chamber, a vent closure member a screw rod supporting saidvent closing member, said screw rod being threaded through thesupporting door of said plate member, and means externally of said dooroperating said rod and said closure member to regulate said vent.

2 Claims, 3 Drawing Figures EXTERNAL REGULATION OF INTERNAL AIR VENTSTRUCTURE FOR HAMMERMILL BACKGROUND AND SUMMARY OF THE INVENTION Agrinding mill of the hammermill type which traditionally was related togrinding feed products has developed significant usefulness in grindinga general variety of materials having industrial application. Manymaterials including many non-agricultural materials for efficienthandling in a hammermill require a regulation of the internal airrecirculation system therein. Hence, the control or regulation ofinternal air flow has significant importance.

It is an object of this invention therefore, to provide an externalcontrol means to regulate the internal air recirculation system of ahammermill.

The internal recirculation of air within a grinding chamber creates alow pressure area at the mouth of the outlet whereby there is a tendencyto create a suction effect with respect to light weight ground materialsuch that a portion of said ground material entering the mouth of theoutlet is drawn back into the grinding cycle within the grinding chamberby action of said internal air recirculation thereby reducing theeffective capacity of said grinding chamber to receive new material.

Hence, it is another object of this invention to improve the efiectivegrinding capacity of a hammermill through the regulation of its internalair recirculation system to more effectively discharge material from thegrinding chamber.

It is also an object of this invention to improve the grindingefficiency of a hammermill by providing a more effective discharge ofground material therefrom by regulation of its internal airrecirculation system.

More generally stated, it is an object of this invention to provide anair valve structure for regulation of the internal air recirculationsystem ofa hammermill which comprises a cover plate forming one side ofthe grinding chamber, an outer door supporting said cover plate in aspaced relation thereto, a vent in said cover plate, a closure memberfor said vent. a rod carrying said closure member. said rod beingthreaded through said door and means externally of said door to operatesaid rod and said closure member to regulate the opening of said vent.

These and other objects and advantages of the inven tion will be setforth in the following description made in connection with theaccompanying drawings in which like reference characters refer tosimilar parts throughout the several views and in which:

FIG. 1 is a broken view in front elevation showing some portions indotted line;

FIG. 2 is a broken view in perspective showing details of interiorstructure;

FIG. 3 is a broken view in central vertical section on an enlarged scaletaken on line 33 of FIG. 1 as indicated.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, ahammermill type of grinding mill is indicated. The invention hereinrelates to the grinding chamber of said grinding mill and moreparticularly to the regulation of the internal air recirculation of saidmill is shown as is believed necessary to support a description of thestructure and function of the invention herein.

Said mill 10 comprises a housing 12 having a top wall 14, front sidewalls 17 and 18 and a front bottom wall 19. A bottom supporting framestructure 20 is indicated.

Hinged onto said front side wall l7 is a conventional manner is an outerdoor 22. Extending from the free ends thereof are said door latchmembers 24 received and secured by keepers or locking members 26 carriedby said side front wall 18. Depending from said bottom wall is an outletor discharge chute 25 having an open top or mouth portion 26 formed inthe bottom of said wall 19.

Within said housing 12 is a chamber 27. Mounted within said chamber in aconventional manner as onto the back wall thereof and spaced inwardlyfrom the bottom and side walls thereof is a screen member 30. Saidscreen member defines the side wall of the grinding chamber 32 therein.An inlet chute 35 feeds into said chamber through the top wall l4.Mounted onto a driving shaft 37 extending inwardly of the back wall 38of said housing within said grinding chamber is a rotor 40 formed ofparallel spaced plate members hav ing hammers 42 respectively pivotallymounted between adjacent of said plate members and spacedcircumfrentially about said rotor.

Said door 22 has mounted thereon in spaced relation thereto a platemember 50 which when said door is in closed position forms a cover orfront wall of said screen 30 and having a configuration to fit withinthe periphery of the leading edge portion of said screen and providing asupport therefor.

Said plate member is held in spaced relation with respect to said doorby a plurality of posts 52 secured therebetween as by welding or bybolts as indicated in FIG. 3.

Formed centrally of said plate member 50 is a circular opening or ventS5. Mounted onto the outer side of said door as by welding in axialalignment with said vent is a post member 60 having a threaded bore.Extending through said post member is a rod 62. Carried by the inner endportion of said rod inwardly of said plate member 50 is a closure member64 for said vent 55. In the embodiment of the invention here presented,said closure member is shown to be a relatively flat cone in form to beself-centering within said vent 55. Said closure member may be rigidlysecured to said interior end of said rod or may be rotatively securedthereto in a conventional manner. as may be desired.

Secured to the outer end portion of said rod is a manually operablemeans 66 here shown as a hand wheel. A sufficient portion of said rod 62will be threaded for axial movement by rotation relative to said postmem ber 60 for regulation of the opening of said vent by an axialmovement of said closure member 64.

OPERATION In operation, the centrifugal action of the rotor 40 and itshammer 42 drive the material being ground around the periphery of thegrinding chamber adjacent the inner surface of the screen 30. The airstream carry ing the material defines a like path and carries out of thescreen the material which has been ground sufficiently to dischargethrough the mesh sides of the screenv The material discharged throughthe screen into the chamber 27 falls in the direction of and dis chargesthrough the outlet 25.

The centrifugal action of the air stream creates a low pressure areacentrally of the rotor and the grinding chamber. The presence of saidlow pressure area results in air passing through the vent 55 from thechamber 27 back into the grinding chamber 32 for a complete cycle ofinternal air recirculation. The rotor travels at a high velocity. Themovement of the air from the chamber 27 through the vent 55 into thegrinding chamber 32 is of sufficient velocity to create a low pressurearea adjacent the mouth 26 of the outlet 25.

In the grinding of heavier materials. such as com. the ground materialhas sufficient weight to discharge through the chute without beingaffected significantly by the low pressure area adjacent said mouthportion 26 of said chute. However, with lighter weight materials. suchas with oats, for example as an agricultural material or with commercialmaterials which are reduced to the fineness of powders or the like, thelow pressure area adjacent the mouth 26 of said discharge chute doeshave significant effect in drawing or sucking out of and away from saidmouth 26 a substantial portion of the material which would otherwisedischarge therethrough. When this occurs, a portion of the materialalready ground and ready for discharge is drawn back with the air streaminto the grinding chamber to take up unnecessarily some of the capacityof the grinding chamber which could otherwise be more effectively usedto receive in its place material being fed therein through the inlet 35.At the same time, the efficiency of the operation of the grindingchamber is impaired in going through the effort of regrinding materialsalready sufficiently ground.

it has been found that with the invention herein the effect of the lowpressure area adjacent the outlet 25 can be controlled so effectively asto have a negligible effect upon various materials being ground anddischarged therethrough by controlling the velocity and- /or the volumeof the air stream passing from the chamber 27 through the vent 55 intothe grinding chamber 32. It has been found that this air stream is veryeffectively regulated by the use of the vent closure member 64 to adjustor regulate the opening of the vent 55. The velocity and the volume ofmoving air moving through the grinding chamber controlled and sloweddown by closing down the vent 55. The extent to which this is done inany given case depends upon the particular material being ground toobtain the most efficient and effective use of the grinding chamber andto obtain a substantially full discharge of ground material through thedischarge chute 25.

The vent closure member 64 is very readily regulated by the hand wheel66 which is external of the door 22 and regulates the position of saidclosure member 64 by means of said screw rod 62.

This invention, although it appears to be very simple in structure,represents and has proved to provide a very significant and effectiveimprovement in the operation of a hammermill and particularly inregulating the internal air recirculation system to obtain a high degreeof grinding capacity within the grinding chamber 32 and a high degree ofefficiency and effectiveness in grinding material through a singlegrinding cycle. The invention herein has proved to be very satisfactoryunder operating conditions.

It will of course be understood that various changes may be made inform, details, arrangement and proportions of the parts withoutdeparting from the scope of the invention herein which, generallystated, consists in an apparatus capable of carrying out the objectsabove set forth, in the parts and combination of parts disclosed anddefined in the appended claims.

What is claimed is:

1. An air valve structure for a hammermill, having in combination ahousing having a grinding chamber therein,

a screen forming the side walls of said grinding chamber,

a plate member forming a front wall of said grinding chamber,

said plate member having a circular opening therein,

a conical closure member regulating the opening of said plate,

a door carried by said housing,

means mounting said plate member on said door in spaced relationthereto,

a rod carrying said closure member at its interior end and having itsouter end portion extending outwardly of said door, and

means on said outer end portion of said rod for moving said closuremember axially of said circular opening.

2. The structure set forth in claim, wherein said outer end portion ofsaid rod has a threaded engagement with and extends through threadedmeans on said door for axial movement in connection therewith.

1. An air valve structure for a hammermill, having in combination ahousing having a grinding chamber therein, a screen forming the sidewalls of said grinding chamber, a plate member forming a front wall ofsaid grinding chamber, said plate member having a circular openingtherein, a conical closure member regulating the opening of said plate,a door carried by said housing, means mounting said plate member on saiddoor in spaced relation thereto, a rod carrying said closure member atits interior end and having its outer end portion extending outwardly ofsaid door, and means on said outer end portion of said rod for movingsaid closure member axially of said circular opening.
 2. The structureset forth in claim, wherein said outer end portion of said rod has athreaded engagement with and extends through threaded means on said doorfor axial movement in connection therewith.